The invention relates generally to ultrasound imaging systems and more particularly to an ultrasound imaging system that can acquire three-dimensional volume data of anatomical structures.
Ultrasound imaging systems are widely used for medical diagnostic applications. In more complex systems, three-dimensional (3-D) volume data of anatomical structures can be ultrasonically acquired, as well as the typical two-dimensional (2-D) images. In such systems, the acquired 3-D volume data can be used to view virtual anatomical structures in different configurations by manipulating the 3-D volume data to display 2-D images. As an example, the 3-D volume data can be viewed by slicing through the displayed volume data at some arbitrary user-specified location or by using one of the available volume rendering algorithms.
A xe2x80x9c3-D ultrasound volumexe2x80x9d is defined herein as a construction of ultrasound information relating to three dimensions of a target. As one example, a 3-D ultrasound volume may be formed by assembling a number of ultrasonically acquired frames (or slices) of pixel data, with each frame representing a cross section along a different plane through the target volume. Combining the frames of pixel data is one approach to providing a 3-D ultrasound volume of 3-D volume data.
During an ultrasound examination using a conventional 3-D ultrasound imaging system, one or more 3-D ultrasound volumes (of B, power, color, etc. information) from an anatomical structure of a patient may be acquired by a sonographer. Each acquired 3-D volume can then be manipulated in different configurations to render multiple 2-D images from the 3-D volume data. These 2-D images are saved for subsequent review by a physician for evaluation or diagnosis. Each viewing configuration of the 3-D volume data requires the input of a set of viewing parameters to define the desired rendering. In general, the 2-D images are captured and saved in a sequential manner during operations in which the 3-D volume data is manipulated to render a different viewing configuration for each subsequent 2-D image. The underlying 3-D volume data for the saved 2-D images may also be saved for subsequent retrieval.
If a particular 3-D volume is saved, the sonographer can capture additional 2-D images from that 3-D volume at a later time. However, the sonographer will have to re-enter the viewing parameters to manipulate the 3-D volume data to a desired viewing configuration, which would typically be the viewing configuration that was defined when the last 2-D image was captured and saved. It can take the sonographer some time to set the right parameters for the desired viewing configuration. It may also be impossible for the sonographer to set the viewing configuration from the previously saved 2-D image. Thus, capturing additional 2-D images from saved 3-D volume data can be a tedious task. Due to this inconvenience, a sonographer is motivated to use the examination time to capture and save all of the 2-D images that may be of interest at a later time. Of course, this prolongs the duration of the examination.
In light of the above concern, what is needed is an ultrasound imaging system and a method of managing the saved 2-D images and their underlying 3-D volume, such that it is more convenient and efficient to acquire additional 2-D images from the 3-D volume data after the initial ultrasound examination.
A system and a method of managing 2-D images, as well as any saved 3-D volume data that was used to derive the 2-D images, utilize a bookmark saver that operates to automatically save, for each 2-D image saved, the settings of viewing parameters for the corresponding 3-D volume data when the 2-D image was saved. The automatic saving feature executed by the bookmark saver ensures that the underlying 3-D volume data, if saved, is retrieved in the viewing configuration that was set when the 2-D image of interest was saved. This feature allows a user of the system to efficiently return to work that was previously suspended or terminated. The system may be an imaging system based on ultrasound, magnetic resonance, computed tomography technology, or other modalities. Alternatively, the system may be a conventional computer system that embodies the bookmark saver.
In an exemplary embodiment, the system includes an ultrasonic scanhead, a processing unit, an input device, and a display device. The scanhead includes an array of piezoelectric elements to transmit sound waves and to receive echoes of the transmitted ultrasound waves that are reflected from an anatomical structure of interest. The scanhead operates to convert the received echoes into electrical signals. The scanhead is electrically coupled to the processing unit, which processes the electrical signals to generate 3-D ultrasound volume data that electronically represents the anatomical structure of interest. The input device functions as a user interface and may include a standard computer keyboard and a pointing device. The display device may be a CRT or an LCD monitor.
The processing unit of the system includes a scanhead controller, memory, the bookmark saver, a removable storage device, a network interface, and a processor. The scanhead controller is operatively connected to the ultrasonic scanhead to control the transmitting and receiving operations of the scanhead. The removable storage device may utilize one of a number of removable storage media that are currently available, such as a writeable CD, a DVD, or a magneto-optical storage medium. Alternatively, the removable storage device may be an on-system storage device, i.e., a hard disk drive.
The bookmark saver of the processing unit is configured to operate with the processor to automatically save the settings of viewing parameters for the underlying 3-D ultrasound volume data whenever a 2-D image is saved. The bookmark saver may be implemented in the processing unit as hardware and/or software. In a preferred embodiment, the bookmark saver operates to embed the information regarding the viewing parameters into a data file called a xe2x80x9cbookmark.xe2x80x9d The bookmark contains the 2-D bitmap data of the saved 2-D image and the information identifying which 3-D ultrasound volume data corresponds to the 2-D image, as well as the viewing parameter information. Since the viewing parameter information and the identifying information are embedded with the 2-D image data, there is no need to store such information in a database.
By storing 2-D images as well as bookmarks, older PACS systems are not precluded from using images generated by the ultrasound imaging system. When the system interacts with PACS, the system can decide to send either 2-D images or 2-D images, bookmarks and volumes, depending on the PACS""s capabilities. The advantage to the physician is that he/she does not have to choose between a bookmark and an image.
The method in accordance with the present invention includes a step in which 3-D ultrasound volume of an anatomical structure of a patient is acquired using known ultrasound 3-D imaging techniques. Next, the acquired 3-D ultrasound volume is manipulated to a viewing configuration using a number of viewing parameters to capture a 2-D image from the 3-D ultrasound volume data. As an example, the viewing parameters may include orientation, geometry, rendering algorithm (e.g., surface rendering and arbitrary slicing), colormaps, and ultrasound imaging parameters. The exact types of viewing parameters that are used to manipulate the 3-D ultrasound volume data are not critical to the invention.
After the 3-D ultrasound volume data has been manipulated to the desired viewing configuration, the 2-D image is saved in accordance with the instructions of the user of the ultrasound imaging system. The 2-D image may be saved in the memory or in the removable storage device of the system or network. In response to the saving of the 2-D image, the bookmark saver of the processing unit automatically saves the viewing parameters. Furthermore, the bookmark saver saves the information that identifies the 3-D ultrasound volume from which the 2-D image was derived. In a preferred embodiment, the 2-D bitmap data of the 2-D image, the viewing parameter settings, and the identification information are collectively saved as a bookmark file. Additional 2-D images may be derived from the acquired 3-D ultrasound volume by changing one or more viewing parameters to manipulate the 3-D ultrasound volume data to a different viewing configuration. Furthermore, additional 3-D ultrasound volumes of the same or a different anatomical structure of the patient may be acquired by repeating the above-described steps. If repeated, one or more 2-D images may be derived from each additionally acquired 3-D ultrasound volume.
Each 3-D ultrasound volume may be saved anytime after that 3-D ultrasound volume is acquired. After all the 3-D ultrasound volumes of interest and the viewing parameters for each desired 2-D image have been saved, one or more of the saved 2-D images can be reviewed by displaying the 2-D images on the display device of the system. Assuming that the underlying 3-D ultrasound volume for a particular 2-D image had been previously saved, the 3-D ultrasound volume can then be retrieved using the saved viewing parameters, such that the 3-D volume is in the same viewing configuration as when the 2-D image was saved.
An advantage of the preferred embodiment of the invention is that since the bookmark contains information that identifies which 3-D ultrasound volume is the underlying data for the 2-D image stored in the bookmark, data regarding the existence of a relationship between the 2-D image and the underlying 3-D volume need not be stored. Instead, the relationship can be inferred by simply searching the system to see if the underlying 3-D ultrasound volume had been saved.
Another advantage is that the retrieved 3-D ultrasound volume is in the same viewing configuration as when a particular 2-D image was saved, which eliminates the need to reset the viewing parameters to manipulate the retrieved 3-D ultrasound volume data to that viewing configuration.